Conventional methods and equipment for preserving red blood cells (RBCs) in the frozen state have been available for many years. The U.S. military has stockpiled several thousand units of frozen group O RBCs for emergency use and may expand these reserves. The civilian blood bank uses for frozen blood include the long-term storage of rare blood types and the storage of RBCs by donors for anticipated future elective surgery. Current standard methods for preservation of RBCs by glycerolizing and deglycerolizing are in use by the military and civilian blood banks (e.g., the American Red Cross and the Naval Blood Research Laboratory Standard Operating Procedures).
In general, the steps involved in the conventional glycerolization/deglycerolization process are as follows: (1) whole blood collection from a donor (e.g., using an anticoagulant); (2) preparation of RBCs from whole blood by removal of plasma (RBCs may be separated, concentrated and stored in additive solution such as AS-1 or AS-3); (3) addition of glycerol cryopreservative to the RBCs prior to freezing; (4) freezing of the glycerolized RBCs for long-term storage (up to about 10 years); and (5) thawing and deglycerolizing of the RBCs (up to about 24 hours of refrigerated storage after deglycerolization, and before centrifugation and administration).
At present, RBCs are glycerolized using a manual procedure involving a bag shaker, centrifuge and plasma extractor (see, e.g., the American Red Cross and the Naval Blood Research Laboratory Standard Operating Procedures). To deglycerolize RBCs, a manual procedure is also used (see, e.g., the Naval Blood Research Laboratory Standard Operating Procedures) involving a centrifugal cell washer (e.g., Model 115; available from Haemonetics Corp., Braintree, Mass.). The Haemonetics system requires one, nearly full-time user to produce about one unit per hour of deglycerolized RBCs. The Haemonetics centrifugal system is not regarded as closed and sterile because it has a rotating centrifuge bowl seal that is open to room air. Therefore, the deglycerolized RBC product from this system must be used within 24 hours or discarded. An additional centrifugation step may be required just before RBC administration to a patient to concentrate the RBCs and remove free plasma hemoglobin.
There is a need in the art for a device that can provide automatic, rapid, sterile, low-cost glycerolization and deglycerolization and long-term storage of deglycerolized RBCs for both military and commercial applications. Such a device would greatly increase the practicality and usefulness of frozen RBCs.
Additionally, current methods for intra-operative autotransfusion utilize a centrifuge to process blood in batches. The methods and applications involve processes which are automatic (e.g., the processing of a full centrifuge bowl), while other processes are manual (e.g., the filling of the bowl and the processing of a less than full bowl). Additionally, the processing parameters for a partially-full centrifuge bowl must be manually set if substantial saline dilution and inadequate waste removal are to be avoided. Conventional, disposable autotransfusion sets are also quite expensive, since most current systems use batch processing of blood in relatively large centrifuge bowls. System set-up is also burdensome, and takes about five minutes. Finally, a trained perfusionist is usually required to operate a conventional autotransfusion system in open heart surgery, when a heart-lung bypass is being used. A technician operates the system for vascular surgery or orthopedic surgery, also adding to the cost of the procedure.
There is therefore a need in the art for a fully automatic, safe, easy to set up and use intra-operative autotransfusion system. Such an apparatus may allow a nurse or anesthesiologist to set up and monitor the system operation during use, saving substantial time and cost.